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Sanborn Creek Project Page 15 August 21, 1992 <br />• TAHLE 4. Predicted maximum "D" and "E" Seam subsidence effects from <br />retreating a single panel in the Sanborn Creek Mine <br />Notes: Effective mining height = 20 feet; Effective depth, "D" Seam <br />= 194 feet (59 meters): Effective depth, "E" Seam = 338 feet (103 <br />meters): Panel width = 520 feet (158 meters); Overburden density = <br />160 PCF (59 meters); Previously unsubsided ground (virgin) assumed, <br />if previously subsided increase predicted subsidence effects by 10 <br />percent; S„~, - maximum vertical subsidence; +E - maximum tensile <br />strain (micro-strain); -E - maximum compressive strain <br />(micro-strain) <br />Mining Robbed Local Single Single Single <br />Depth Pillar Extraction Panel Panel Panel <br />feet Width percent S,,,a, +E -E <br />(meters) feet feet (ut) (ut) <br />Low-cover - 1250 feet <br />"C" to "D" Seam <br />194 20 81 8.8 29400 23000 <br />(59) <br /> 40 68 6.7 21600 17000 <br /> "C" to "E" Seam <br />338 20 81 8.5 16300 12800 <br />(103) <br /> 40 68 6.2 12000 9400 <br /> "C" Seam to Gro und Surface <br />1250 20 81 3.9 2360 5000 <br />(381) <br /> 40 68 2.9 1740 3690 <br /> High-cover - 2500 feet <br /> "C" to "D" Seam <br />194 50 60 6.9 23200 18200 <br />(59) <br /> 80 33 5.1 17000 13300 <br /> "C" to "E" Seam <br />338 50 60 6.7 12900 10100 <br />(103) <br /> 80 33 4.9 9400 7380 <br /> "C" Seam to Gro und Surface <br />2500 50 60 0.94 200 850 <br />(762) <br /> 80 33 0.69 140 620 <br /> <br />